Rumored to have first been served in Los Angeles in the 1950s, the Monte Cristo sandwich is still a staple on the lunch menu at Disneyland’s Blue Bayou restaurant. There are many ways to make this sandwich, including deep-frying it, but here we’ve presented a basic method for pan-frying that’s much simpler. Don’t forget the red currant jelly—it’s not optional! Its sweet tang cuts through the salty, gooey richness of the French toast and filling.
Place the egg and milk in a wide, shallow plate and season with salt and pepper. Whisk until the egg is broken up and evenly incorporated; set aside.
Place 2 slices of the bread on a work surface and spread 1 teaspoon of mustard on each. Divide the ham and turkey between the mustard-coated bread slices. Place half of the cheese on top of each pile of meat. Close the sandwiches with the remaining 2 slices of bread. Press gently on the tops of the sandwiches to compact slightly.
Melt the butter in a large nonstick frying pan over medium-low heat until foaming. Using your hands, place 1 sandwich in the reserved egg mixture, flipping to coat both sides. Place the sandwich in the frying pan. Repeat with the second sandwich.
Fry undisturbed until the bottoms of the sandwiches are golden brown, about 4 to 5 minutes. Flip and fry until the other side is golden brown and the cheese is melted, about 4 to 5 minutes more.
Transfer to serving plates, dust with powdered sugar, and serve with red currant jelly.